Up to now, methods of wirelessly accessing the Internet include a method of gaining access through a mobile telephone network based on a platform such as Wireless Application Protocol (WAP) or Wireless Internet Platform for Interoperability (WIPI), and a method of gaining access using a public wireless Local Area Network (LAN) and an access point. However, the method using a mobile telephone network has fundamental limitations when used as a universal Internet access means due to limitations related to screen size and the input interface, a measured rate-based charging system, etc. The method using a wireless LAN has fundamental problems in that it has a spatial limitation in that it can be used only within a radius of several tens of meters around an access point, and in that mobility is poor. In order to overcome the problems, Wireless Broadband Internet (WiBro) has been proposed as wireless Internet service that enables fast Internet access when not moving or when moving slowly, at Asymmetric Digital Subscriber Line (ADSL)-level quality and cost.
FIG. 1 is a diagram illustrating a resource allocation method of allocating resources based on time and frequency axes in an OFDMA method. Since radio resources, including time and frequency, are limited in a general communication system, the radio resources should be distributed to and then used by a plurality of terminal users. However, the portable Internet system adopts OFDMA, unlike systems such as the existing Code Division Multiple Access (CDMA) series and Wireless LAN (WLAN). OFDMA is a method of allocating two-dimensional resources, defined along time and frequency axes, to respective terminals, as illustrated in FIG. 1.
FIG. 2 is a diagram illustrating the MAP architecture of a portable Internet system. As illustrated in FIG. 2, the portable Internet system transmits pieces of data which use the same channel coding and modulation schemes in one bundle so as to increase efficiency. A set of data areas using the same channel coding and modulation schemes is referred to as one burst, and information about the location and size of each burst can be known through the MAP information of a frame, as illustrated in FIG. 2. Here, the term frame refers to a structured data sequence having a fixed duration which is used according to physical layer standards. A single frame may have both a downlink (DL) sub-frame, which is a link from a base station to a mobile station, and an uplink (UP) sub-frame, which is a link from a mobile station to a base station.
Since the portable Internet system adopts Time Division Duplex (TDD), in which transmission via an uplink and transmission via a downlink share the same frequency and are performed at different times, essential information, such as the length of one frame and the ratio of a downlink and an uplink to each other, is provided through the MAP information. A base station may transmit different MAPs via respective frames so as to dynamically allocate resources to respective terminals. In this case, each MAP may be divided into a DL_MAP having transmission information for the downlink, and a UL_MAP providing notification of resource access authority for an uplink. Here, the DL_MAP can be defined as a media access control layer message that defines the symbol offsets and sub-channel offsets of bursts, which are obtained through division and multiplexing on sub-channel and time axes by a base station on a downlink, and the numbers of symbols and the numbers of sub-channels, in which the symbols and the sub-channels are allocated resources. The UL_MAP can be defined as a set of pieces of information that define the entire connection for an uplink portion.
Meanwhile, the location information of the DL_MAP can be known using a predetermined different method, and the location information of the UL_MAP can be known only through the interpretation of the information of the DL_MAP. In the case of a downlink, a terminal analyzes MAP information defined in conformity with the standard specifications, and thus acquires information about a burst area containing desired content and parameters for an access method. In order to access information contained in each burst, the location information of the burst designated by the MAP must be considered, and a demodulation procedure must be performed according to a corresponding channel coding scheme (Convolutional Coding (CC), Convolutional Turbo Coding (CTC), Low Density Parity Check (LDPC) Coding, etc.), a corresponding coding transmission rate (½, ⅔, ¾, ⅚, etc.) and a corresponding modulation scheme (QPSK, 16QAM, 64QAM, etc.).
Meanwhile, since a measuring instrument for signal quality analysis at a base station of a portable Internet system focuses on signal analysis at a physical layer level, such a complex procedure has not been considered. However, in the case of an OFDMA-TDD-based system, such as the portable Internet, if the system does not know MAP information, the provision of reliable information at the physical layer level cannot be guaranteed. For example, in the case of Error Vector Magnitude (EVM), accurate analysis can be made for the provision of useful information, an only when burst location information in a frame and a modulation method are known.
FIG. 3 is a diagram illustrating a prior art advanced method of analyzing portable Internet signals in a measuring instrument. As illustrated in FIG. 3, the prior art advanced measuring instrument adopts a method in which, in a state in which a user knows in advance various pieces of information, such as a modulating method and the location information of a burst for an input signal, the user directly inputs the information through the input interface screen of a personal computer, as illustrated in FIG. 3, performs designation, and then analyzes it, that is, a manual burst analysis method.
However, the above method has disadvantages in that the user must directly manage the related parameters of all the waveform files which were created for testing, a lot of time is taken and analysis is inaccurate when manipulation is unskilled, and accurate analysis is impossible because the location information of each burst, a modulation method and the time ratio of an uplink and a downlink to each other may be dynamically changed in an actual communication system. Furthermore, since a separate personal computer, which is equipped with an interface connected to a measuring instrument and configured to receive the manual input of various pieces of information for signal analysis from the user, is required, in addition to the measuring instrument, there is a problem in that the system becomes complicated.